Structure and dynamic association of an assembly platform subcomplex of the bacterial type II secretion system

Régine Dazzoni; Yuanyuan Li; Aracelys López-Castilla; Sébastien Brier; Ariel Mechaly; Florence Cordier; Ahmed Haouz; Michael Nilges; Olivera Francetic; Benjamin Bardiaux; Nadia Izadi-Pruneyre

doi:10.1016/j.str.2022.12.003

Structure and dynamic association of an assembly platform subcomplex of the bacterial type II secretion system

Structure. 2023 Feb 2;31(2):152-165.e7. doi: 10.1016/j.str.2022.12.003. Epub 2022 Dec 30.

Affiliations

¹ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France.
² Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biochemistry of Macromolecular Interactions Unit, 75015 Paris, France.
³ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France.
⁴ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Crystallography Platform, 75015 Paris, France.
⁵ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Biological NMR and HDX-MS Technological Platform, 75015 Paris, France.
⁶ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris. Electronic address: benjamin.bardiaux@pasteur.fr.
⁷ Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 75015 Paris, France; Institut Pasteur, Université Paris Cité, CNRS UMR3528, Bacterial Transmembrane Systems Unit, 75015 Paris. Electronic address: nadia.izadi@pasteur.fr.

PMID: 36586404
DOI: 10.1016/j.str.2022.12.003

Abstract

Type II secretion systems (T2SSs) allow diderm bacteria to secrete hydrolytic enzymes, adhesins, or toxins important for growth and virulence. To promote secretion of folded proteins, T2SSs assemble periplasmic filaments called pseudopili or endopili at an inner membrane subcomplex, the assembly platform (AP). Here, we combined biophysical approaches, nuclear magnetic resonance (NMR) and X-ray crystallography, to study the Klebsiella AP components PulL and PulM. We determined the structure and associations of their periplasmic domains and describe the structure of the heterodimer formed by their ferredoxin-like domains. We show how structural complementarity and plasticity favor their association during the secretion process. Cysteine scanning and crosslinking data provided additional constraints to build a structural model of the PulL-PulM assembly in the cellular context. Our structural and functional insights, together with the relative cellular abundance of its components, support the role of AP as a dynamic hub that orchestrates pilus polymerization.

Keywords: assembly platform; ferredoxin-like fold; protein-protein interaction; type II secretion system; type IV pili.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacteria / metabolism
Bacterial Proteins / chemistry
Fimbriae, Bacterial / metabolism
Type II Secretion Systems* / metabolism

Substances

Type II Secretion Systems
Bacterial Proteins